First of all, it's getting a huge patch tomorrow which should, assuming we believe the
patch notes should fix a ton of smaller issues, and many gamebreaking ones (though I don't think I had the misfortune of running into any of the big issues).
Gameplay wise it's a lot more dynamic. And flexible. The jump pack adds verticality, open world means you can get to where you want to get most of the time, this.. makes the game great as a shooter - not a tactical shooter mind you, squad orders are almost gone, as well as the "let's pause and think of a strategy and give orders" screen. This gave the game almost a "Far Cry" 3/4 vibe, where you see an enemy base in the distance and can approach it however you like - you can crash into it in the Nomad, guns blazing. You can pick off sentries with the sniper rifle. You can infiltrate, jump on the roof and start shooting them as they try to reach your position.
Character development however is imo the best in all the series. I'd like for there to be more than just combat skills, but that's the grumpy oldschool rpg fan talking, for what it is - it's great. Powers now can be combined into combos that deal massive dmg, so you can still dish it out as a biotic. Thing is this time, you don't have to specialize at all. You have these "profiles" that unlock as you put more points into the skill trees (combat, tech, biotic). Each profile adds several bonuses as well as an unique one, has multiple stages. Each profile has 3 power slots. Profiles can be changed on the fly using the F keys. This means you can enter the fight as a biotic, lift eveything up, then switch to a saboteur, technician or spy profile (or whatever) and set up turrets beneath them that will keep them occupied why they float around. And through all that, you can keep using whatever weapon you fancy, as there are no restrictions here.
I will come back to this probably rather sooner than later and my plan is to test out a biotic with only a pistol - the soldier/tech combo proved very powerful, in fact it was so powerful I don't think I died in combat more than twice during the whole game. I fell into bottomless pits quite a lot, but luckily that only teleports you back (with no shield) to where you jumped off of. Did I mention there is a lot of jumping ? There's a lot of jumping! Anyway, on normal the game is ...well, easy, and I think it would be just as easy for every class.
If you want it to be just as easy, when you're researching new weapons, look up the Dhan Shotgun. Small clip, weird acting ammo (takes some time getting used to, but not too much), short range (duh) but absolutely ridiculous damage. One shotting most regular opponents, 2 shotting elites and taking down brutes like the Fiend (biggest bullet sponges in the game) with 10 or so rounds. It's just silly. Thing is, you need to learn how to aim - it only holds 2 rounds and the reload is ridiculously long. Or at least feels like it when you have a charging beast in front of you and an empty clip :P